Algorithms

AN2334

8/22

Figure 2.

VNH2 PWM signal

At this point the system waits for any event: A pressed key or a pinch.

If a key is pressed, the motor is stops, resetting VNH2 PWM and setting InA and InB for

braking to Vbatt the motor and stopping the glass.

In case of a pinch event, the Window Up switch is first checked. If this switch is closed

(upper limit reached), the glass is locked driving the motor up for 800 ms.

Otherwise, if the glass moves up, it is driven down for 800 ms to release the pinched object;

if it goes down the motor is stopped immediately.

When an abnormal condition is detected (Open Load, Short circuit or thermal shutdown), a

LIN message is sent to the PC VNH2 diagnostic node. Open Load is detected by current

sense voltage monitoring (value) while a short circuit and thermal shutdown are detected

using the VNH2 DIAGx pin. When DIAGx pin is reset, while INx is set, the status pin

indicates a thermal shutdown; otherwise, if INx is reset the status pin detects a short circuit.

For further information about antipinch algorithms, please refer to “AN2095 - VNH2 for

window lift with antipinch routine”.

When a command for L9950 loads is detected through keypad input pins, the

microcontroller drives such loads through the L9950 SPI bus. Serial data for controlling

outputs and for receiving status registers is sent via this bus.

For example, if one of the over-current bits is set, the corresponding driver is disabled. If the

over-current recovery bit of the output is not set, the microcontroller must clear the over-

current bit to enable the driver again.

If the thermal shutdown bit is set, all drivers go to high impedance state. Again, the

microcontroller must clear the bit to enable the drivers.

When the Fold Mirror motor is activated, the relevant motor is driven for 4 seconds with a

fully charged battery and for 6 seconds in other cases. Since the OUT1 is common to all

mirror motors, it is impossible to drive two or more mirror motors at the same time.

The turn indicator and the defroster are driven using PWM2 and PWM1 respectively.

For all lights, the over-current Recovery Enable bit is set by the microcontroller; this

automatically reactivates the output after a delay time, resulting in a PWM modulated

current with a programmable duty cycle.

The over-current recovery feature is intended for loads which have an initial current higher

than the over-current limit of the output (for example, cold light bulbs).

The described algorithm, including LIN message managing, is stored in less than 10 kB on

the microcontroller Flash memory.

t

Soft Start

5V

PWM

Duty

Cycle

30%

Duty

Cycle

50%

Duty

Cycle

70%

Duty

Cycle

100%